Presence information is a status indicator that conveys ability and willingness of a potential communication. Presence systems are used today to acquire information about a user. Currently, presence services mostly utilize session initiation protocol (SIP) to transport presence information from a user device to a server in the network. A presence aggregation service collects presence data from multiple sources and mobile devices to create an aggregated view of a user's presence in a centralized network presence server. Enterprise and third party unified communications platforms can access the aggregation server to acquire users' presence information. However, relying on SIP to publish presence updates has many drawbacks.
For example, some mobile phones do not support SIP. In addition, due to the fact that enterprises may operate over many cellular operators or WiFi hot spots, SIP support may vary. Requiring a SIP stack in the mobile device provides additional demands on the native platform and could restrict deployment of presence enabled applications. SIP clients can also be very costly and middleware components are generally more difficult to deploy than application level components.
In addition, SIP protocol being more verbose than other messaging protocols tends to transmit a relatively large number of messages. As a result, SIP consumes a relatively high level of bandwidth. The exchange of a relatively large number of messages also has a detrimental effect on battery life of the mobile device.